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5.2 Application Development
This section contains information related to application development for ecosystem components and MapR products including MapR-DB (binary and JSON), MapR-FS, and MapR Streams.
Connecting to the Cluster
Application are often run on nodes that are not part of the MapR Cluster. There are many methods to connect to a MapR cluster; this section will briefly describe each option.

MapR 5.2 Documentation

5.2 Application Development
This section contains information related to application development for ecosystem components and MapR products including MapR-DB (binary and JSON), MapR-FS, and MapR Streams.
- Connecting to the Cluster
  Application are often run on nodes that are not part of the MapR Cluster. There are many methods to connect to a MapR cluster; this section will briefly describe each option.
  - Application Connections to the Cluster
    The MapR client connects to the cluster via CLDB nodes. When a connection attempt fails, the MapR client returns an error. When an existing connection is no longer available, the MapR client attempts to reconnect to a CLDB node.
  - Using the MapR-FS JAR to Connect to the Cluster
    The MapR-FS JAR file includes the MapR client libraries required to connect to the cluster. While this is strongly discouraged, application developers can bundle the MapR-FS JAR file in MapR-FS, MapR-DB, and MapR Streams applications instead of installing the MapR client on the edge node (node that runs the application). Applications should not bundle the MapR-FS JAR file unless the application meets certain requirements.
- MapR-FS and Applications
  The following sections provide information about accessing MapR-FS with C and Java applications.
- MapR-DB and Applications
  This section contains information on developing client applications for binary and JSON tables.
- MapR Streams and Applications
  MapR Streams brings integrated publish/subscribe messaging to the MapR Converged Data Platform.
- MapReduce and Applications
  This section contains information associated with developing MapReduce programs or YARN applications.
- Ecosystem Components
  The following sections provide information about each open source project that MapR supports.
- Maven and MapR
  This section discusses topics associated with Maven and MapR.
- Developer's Reference
  This section contains in-depth information for the developer.
- API Documentation
  This topic provides links to the locations of MapR's public APIs. These APIs are available for application development purposes.

Connecting to the Cluster

Application are often run on nodes that are not part of the MapR Cluster. There are many methods to connect to a MapR cluster; this section will briefly describe each option.

MapR Client: The MapR client includes the libraries and utilities required on an edge node to perform the following: connect to the cluster, submit MapReduce jobs, submit YARN applications, run hadoop fs commands, and run hadoop mfs commands. However, to run applications that access data from MapR-DB or MapR Streams, you must configure additional dependencies. For more information about the MapR client, see MapR Client and Application Connections to the Cluster.
NOTE: Although it is not recommended, you can include the MapR-FS JAR file in the application instead of installing the MapR client. However, there are caveats and specific requirements to make this work. For information, see Using the MapR-FS JAR to Connect to the Cluster.
MapR Persistent Application Client Container (PACC): The MapR Persistent Application Client Container (PACC) is a Docker-based container image that includes a container-optimized MapR client. The PACC provides seamless access to MapR Converged Data Platform services, including MapR-FS, MapR-DB, and MapR Streams. The PACC includes the POSIX client, the MapR client, and the libraries required to build MapR-DB and MapR Streams applications. For more information, see About the MapR Persistent Application Client Container (PACC).
MapR POSIX Clients: MapR POSIX clients enable app servers, web servers, and other client nodes and applications to read and write directly and securely to the MapR-FS. For more information about the POSIX clients, see POSIX Clients and MapR POSIX Clients.
MapR NFS Clients: You can mount the cluster itself via NFS so that your applications can read and write data directly. For more information, see Setting Up MapR NFS.